1. Field of the Invention
The present invention relates to an integrated gas control device which is integrated on a panel for the desired uses such as a gas supply control, a gas cleanup or the like in a gas control device of a high purity gas system for a semiconductor manufacturing apparatus.
2. Description of the Related Art
In a gas control device of a high purity gas system for a conventional semiconductor manufacturing apparatus, independent gas control units are connected by couplings and pipes to compose a gas control line and many gas control lines are arranged on a base plate in parallel to integrate the gas control units in panel form. FIG. 1 shows a part of the above described gas control device and a filter 2, a valve 3, a block valve 4, and a mass flow controller 5 are arranged on the base plate 1 from the upstream of the gas flow. As an example, these gas control units are connected to each other by pipes 6, 7 and a coupling 8 shown in FIG. 2. That is, a pipe 6 is butt-welded to the gas passage of a passage block for connecting one gas control unit and a pipe 7 is butt-welded to the gas passage of a passage block for connecting the other gas control unit, then a metal gasket 12 having a gas passing hole 11 is disposed between annular sealing beads 9 and 10 formed on the end surfaces of the connecting flanges of the pipes 6 and 7 and the connecting flanges of the pipes 6 and 7 are fastened by the male thread 8a and the nut 8b of the coupling 8 and are connected to each other in a sealed state.
Since the independent gas control units of the conventional gas control device are connected by the pipes and couplings in this way, the gas control line is made long and the inner volume of the gas control device in the semiconductor manufacturing apparatus is increased. Moreover, the gas control lines are composed of different passages, but it is difficult to remove and to mount the gas control units and hence a total manufacturing lead time for designing, manufacturing, and assembling them is made longer and an initial start-up period when a semiconductor manufacturing apparatus is newly installed is made longer and many man-hours are required for manufacturing, which increases cost. Moreover, since it is difficult to replace the gas control unit, even if the flow passage needs to be changed, it can not be changed. In the aspect of performance, welding fumes or particles are produced to make a weld zone brittle and to make the life of the piping shorter and, in the aspect of cost, a product yield is low and a maintenance cost is high. Further, since the gas control device can not be made compact, when it is constituted in panel form, it must be arranged on the obverse surface and the reverse surface or in many layers in most cases.
Furthermore, when the individual independent gas control unit is connected to a passage block in the gas control line of the gas control device, it has been generally connected by using a flange coupling or by fastening a plurality of bolts. However, when the bolts are fastened in these connecting methods, they are apt to be partially fastened to reduce reliability and to increase assembling man-hours, which increases cost.